1. Field of the Invention
having a
The present invention relates to a sorter having a finishing function, and more particularly, to a sorter a finishing function wherein sheets ejected from a copying machine, a laser printer or the like are distributed in a plurality of bins and bound by a stapler or the like.
2. Description of Related Art
Recently, responding to the increasing demand for automated paper handling systems for copying machines, optional systems such as an automatic document feeding system and a sorting system designed for sorting or grouping copied sheets have been developed and commercialized in various types. The users of the copying machines are now requiring a sorter-finisher capable of automatically binding and stacking sheets. By request, a sorter-finisher having simple construction was disclosed by U.S. Pat. No. 4,811,048.
Incidentally, in such a sorter-finisher wherein sheets stored in the bins are automatically taken out thereof and transported to the staple tray to be stapled, it is an issue how to control the mechanism when a trouble such as a paper jam occurs during the sheet transportation from each of the bins to the staple tray. Generally when such a trouble occurs, an operator takes the sheets out of the bin where the trouble occurred. However, if the finisher-sorter is so constituted that after treatment of the trouble, the operation is resumed with the bin where the trouble occurred, the operation may be discontinued again because there are no sheets in the bin, and the operation is never proceeding.
Also, the sheets in the bin where a trouble occurred are not always taken out thereof by an operator, and the sheets are sometimes set in the bin again. Accordingly, the sorter-finisher should have a proper control system so that the operation is resumed in a proper way, according to the way of treating the trouble, or the state of the bin where the trouble occurred.
Further, in such a sorter-finisher, a stapling operation is not prepared until it is confirmed that there are sheets in the bins of the sorter. Conventionally, a photosensor whose optical axis penetrates all the bins is provided for the sorter to check the existence of sheets. However, in this way of detecting sheets, if there are sheets in at least and one of the bins, the existence of sheets is confirmed. Therefore, even when the sheets are taken out of one of the bins, it is impossible to detect. It sometimes happens that sheets are taken out of a bin by an operator who is in a hurry so that the sheets will be stapled manually, and in such a case, when the bin where the sheets has taken out by the operator is to be subjected to the stapling operation, the occurrence of a trouble is judged, which causes discontinuance of the operation.